This patent application is co-pending with one related patent application entitled xe2x80x9cLINE CHARGE ASSEMBLY AND SYSTEM FOR USE IN SHALLOW-WATER CLEARING OPERATIONSxe2x80x9d (Navy Case No. 82565), by the same inventors as this patent application.
The invention relates generally to systems for clearing mines and other obstructions from a shallow-water area, and more particularly to a line charge assembly and system used to clear a shallow-water area that is automatically disabled after a prescribed period of time during which detonation does not occur and that is equipped to prevent sympathetic detonation of any of such assemblies having a dud fuze.
Surf zone mine clearing operations involve the placement of a large number of charges over an area that will define a safe lane of travel for follow-up traffic. Ideally, these charges are placed from a safe stand-off distance, are reliably detonated, and rendered inoperable if they do not detonate. One system being considered for these operations is a line charge assembly that is launched from a watercraft into a surf zone. A number of such assemblies would be deployed and then detonated to clear mines and other obstructions from an area. Following detonation, another set of line charge assemblies would be deployed in an area adjacent to the just-cleared area. To ensure total clearing, the area to be cleared is defined to partially overlap the area just cleared. However, this system presents two substantial problems.
The first problem is inherent to any explosive system. That is, each line charge assembly must be fuzed to prevent its unintended detonation during shipping, storage and deployment. Further, the fuze must initiate detonation only at a specified time and in specified conditions, and is still further required (by a variety of ordinance guidelines and standards) to disable any possible detonation after the specified time period has lapsed. Thus, the fuze must be xe2x80x9csafedxe2x80x9d if it is a dud where xe2x80x9csafedxe2x80x9d means that the fuze""s primary energetic components cannot transfer detonation energy to the fuze""s explosive train that contains less energetic materials.
The second problem is one brought about by the nature of the above-described operation. Specifically, when a watercraft is to deploy line charge assemblies in an area that is adjacent to a just-cleared area, the watercraft may have to enter the just-cleared area in order to deploy its line charge assemblies in the proper overlap zone. If there is (are) xe2x80x9cdudxe2x80x9d fuze(s) in the just-cleared area, the deploying watercraft could be positioned over undetonated line charges when in the overlap zone. Accordingly, it is imperative that undetonated line charges be prevented from sympathetic detonation in the overlap zone even when a line charge assembly""s fuze is a dud.
Accordingly, it is an object of the present invention to provide a line charge assembly and system for use in shallow-water obstruction clearing operations.
Another object of the present invention is to provide a line charge assembly that can be reliably detonated in accordance with specified conditions.
Still another object of the present invention is to provide a line charge assembly that is reliably xe2x80x9csafedxe2x80x9d in its pre-use condition and in its dud condition.
Yet another object of the present invention is to provide a line charge assembly and system that is equipped to prevent sympathetic detonation of line charges in at least a portion of the line charge when the line charge assembly""s fuze is a dud.
Other objects and advantages of the present invention will become more obvious hereinafter in the specification and drawings.
In accordance with the present invention, a line charge assembly and system are provided for use in a shallow-water obstruction clearing operation. Each assembly has a propulsion unit capable of flight through the air, a line charge array, an air-safed water-armed fuze, a first interrupter disposed between the line charge array and the fuze, and a second interrupter disposed in the line charge array. The propulsion unit pulls the line charge array, the interrupter and fuze through the air to a water destination. The line charge array is defined by a plurality of line charges successively coupled to one another by a detonation line capable of transferring detonation energy therealong successively to each line charge. The line charge array has a first end coupled to the propulsion unit and has a second end coupled to the first interrupter. The air-safed water-armed fuze generates the detonation energy at the expiration of a first time period provided the fuze is in water. The first interrupter permits the detonation energy to be transferred from the fuze to the second end of the line charge array until the expiration of a second time period, and then prohibits the detonation energy to be transferred from the fuze to the second end after the expiration of the second time period. The second interrupter permits the detonation energy to be transferred therethrough until the expiration of a third time period, and then prohibits the detonation energy to be transferred therethrough after the expiration of the third time period. The first time period commences when the propulsion unit begins to pull the fuze through the air, the second time period commences when the propulsion unit begins to pull the first interrupter through the air and the third time period commences when the propulsion unit begins to pull the second interrupter through the air. The assembly is configured so that the first time period expires before the expiration of the second and third time periods, both of which can expire approximately simultaneously. In use, a plurality of the line charge assemblies are deployed and detonated in an area. The first interrupter operates independently of the fuze to essentially sterilize a dud fuze. The second interrupter operates independently of the fuze and first interrupter to prevent the back propagation of sympathetic detonation energy to any of the assembly""s line charges that reside between it""s fuze and the first interrupter in the case where the fuze is a dud.